Should an electrocardiogram (ECG) be obtained in a patient after a seizure?

ECG After Seizure: Clinical Utility and Recommendations

Yes, an ECG is helpful and should be obtained in patients presenting after a seizure to identify potentially life-threatening cardiac conditions that can masquerade as seizures and to detect channelopathies that increase risk of sudden death.

Primary Rationale for ECG in Post-Seizure Patients

An ECG should be obtained in all patients presenting with seizures or suspected epilepsy to rule out cardiac syncope masquerading as seizure activity, particularly long QT syndrome and other arrhythmogenic conditions that can cause convulsive syncope. 1 This is critical because:

• Brief seizure-like activity commonly occurs during cardiac syncope, but when the history clearly indicates syncope, this does not require neurologic investigation or EEG 1
• Patients with epilepsy should undergo ECG screening to identify neurological channelopathies that affect both cardiac and brain ion channels 1
• ECG abnormalities are significantly more common in epilepsy patients compared to healthy populations 2

Specific Cardiac Findings That Justify ECG Use

Channelopathies and Arrhythmogenic Patterns

Post-ictal ECGs reveal abnormalities that may be concealed on routine testing:

• Brugada ECG pattern occurs at 10-fold higher prevalence in seizure patients compared to the general population, particularly on post-ictal ECG 2
• QT prolongation is found in approximately 17% of patients during the post-ictal period 2
• Prolonged QTc interval predicts all-cause mortality in patients evaluated for seizure and those diagnosed with epilepsy (Cox HR 1.48; 95% CI 1.37-1.59) 3
• Early repolarization patterns and right precordial abnormalities occur in 3-4% of post-seizure patients 2

Timing Considerations

ECG abnormalities are significantly more pronounced immediately after a seizure compared to an ECG recorded 48 hours later (p = 0.003) 2. This means:

• Post-ictal ECG may unmask disease-related alterations otherwise concealed 2
• In one study, 52 patients had abnormal post-ictal ECGs but only 28 had abnormal basal ECGs 2
• All patients with abnormal basal ECG also had abnormal post-ictal ECG, but not vice versa 2

Cardiac Arrhythmias During and After Seizures

Prevalence of Cardiac Changes

• Heart rate increases of at least 10 beats/minute occur in 73% of seizures (93% of patients) 4
• In 23% of seizures (49% of patients), heart rate increase precedes both electrographic and clinical seizure onset 4
• ECG abnormalities occur in 26% of seizures (44% of patients) 4

Life-Threatening Arrhythmias

Ictal bradycardia and asystole, though rare, represent potentially fatal complications:

• Ictal bradycardia (<40 beats/min) occurs in 2.1% of recorded seizures 5
• Potentially fatal asystole occurs in 16% of patients with refractory focal seizures monitored long-term 5
• 21% of patients with refractory epilepsy required permanent pacemaker insertion due to peri-ictal cardiac abnormalities 5

Diagnostic Yield and Clinical Impact

Detection of Missed Cardiac Pathology

Cardiologist review of ECGs in first seizure clinics identifies significant abnormalities missed by neurologists:

• 28 ECGs thought normal by neurologists were considered abnormal by cardiologists 6
• Three cases of long corrected QT interval were missed by neurologist interpretation 6
• Cardiologist input into first seizure clinics is recommended to enhance diagnostic yield 6

Current Practice Gaps

• Only 57.4% of patients evaluated for seizure or epilepsy receive an ECG 3
• US guidelines do not mandate ECG use in diagnostic evaluation of seizures or epilepsy, despite evidence of benefit 3

Distinguishing Cardiac Syncope from Seizure

When evaluating loss of consciousness:

• Tilt-table testing with simultaneous EEG and hemodynamic monitoring is reasonable (Class IIa) to distinguish among syncope, pseudosyncope, and epilepsy when diagnosis remains unclear 1
• Morning orthostatic blood pressure measurements and carotid sinus massage are integral to initial evaluation 7

Special Context: Post-Cardiac Arrest Seizures

In post-cardiac arrest patients, EEG (not ECG) is the primary monitoring tool for seizure diagnosis:

• Class I recommendation to promptly perform and interpret EEG in patients who do not follow commands after ROSC 1
• However, continuous cardiac monitoring remains essential given the 10-35% incidence of seizures and need to distinguish seizure activity from ongoing cardiac dysfunction 1

Practical Implementation Algorithm

1. Obtain 12-lead ECG at index evaluation for all patients presenting with seizure 1, 3
2. Ideally obtain ECG in the immediate post-ictal period (within hours of seizure) to maximize detection of transient abnormalities 2
3. Have cardiologist review all ECGs from seizure patients, particularly looking for:
   • QTc prolongation (>450 ms in men, >460 ms in women) 2, 3
   • Brugada patterns (especially Type I) 2
   • Early repolarization patterns 2
   • Conduction abnormalities 4
4. Consider repeat basal ECG 48 hours later to determine if abnormalities persist 2
5. If cardiac channelopathy suspected, consider genetic testing and cardiology referral 2

Common Pitfalls to Avoid

• Do not rely solely on neurologist ECG interpretation - cardiologist review significantly improves detection of life-threatening conditions 6
• Do not skip ECG because patient has "typical" seizure history - cardiac syncope with convulsive activity is common and ECG abnormalities occur regardless of final diagnosis 6
• Do not obtain only a single basal ECG - post-ictal timing increases diagnostic yield for channelopathies 2
• Do not dismiss borderline QTc values - even modest QT prolongation predicts mortality in this population 3